Head injury and hemorrhage, either alone or in combination, are responsible for over 60% of the deaths due to trauma and are the primary causes of hospital admission after severe injury. Intravenous fluid therapy is necessary in all of these patients, especially those who require resuscitation from hypovolemic shock. While there is much information about the effects of intravenous fluid therapy on the lung and the kidney, there has been little investigation of the immediate and late effects of intravenous fluids on either the normal or the injured brain. This proposal seeks to determine if differences in fluid osmolality and oncotic pressure affect intracranial pressure, cerbral blood flow, cerebral electrical activity and cerebral water content in a procine model of hemorrhagic shock and head injury. The fluids to be compared are Ringer's lactate, hypertonic sodium lactate, 6% hydroxyethyl starch in 0.9% sodium chloride, and 7.5% hypertonic saline in 6% dextran 70 (4 m1/kg) followed by either Ringer's lactate, hypertonic sodium lactate or 6% hydroxyethyl starch in 0.9% sodium chloride. Each fluid will be studied in three groups of animals: hemorrhage without cerebral injury, cerebral injury without hemorrhage and cerebral injury with hemorrhage. The duration of study will be 24 hours. Data derived from this study will provide substantive information about the most appropriate fluid therapy for patients with head injury. This information will apply not only to those patients requiring massive fluid resuscitation, but also to those patients who have a head injury and require maintenance intravenous fluid therapy. Such information may lead to a reduction in the morbidity and mortality of head injury.